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R.F Magnetron Sputtering법으로 제조한 TiO<sub>2</sub> 박막의 특성
추용호,최대규,Chu Y. H.,Choi D. K. 한국재료학회 2004 한국재료학회지 Vol.14 No.11
Titanium oxide thin films were prepared on Si(100) substrates by R.F. magnetron reactive sputtering at $30\sim200watt$ R.F power range, and annealed at $600^{\circ}C\sim800^{\circ}C$ for 1 hour. The properties of $TiO_2$ thin films were analyzed using x-ray, ${\alpha}-step$, ellipsometer, scanning electron microscopy, and FT-IR spectrometer. Upon in-situ depositions, the initial phase of $TiO_2$ thin film showed non-crystalline phase at R.F. power $30\sim100$ watt. The crosssection of $TiO_2$ thin films were sbserved to be the columnar structure. With the increasing R.F power and annealing temperature, the grain size, crystallinity, refractive index, and void size of titanium oxides showed a tended to increase. The FT-IR transmittance spectra of titanium oxide thin films have the obsorption band of Ti-O bond, Si-O bond, Si-O-Ti bond and O-H bond. With the increase of R.F. power and annealing temperature, these films have the stronger bond structures. It is considered that such a phenomena is due to phase transition and good crystallinity
추용호,이민호,배태성,김태조 大韓齒科器材學會 1995 대한치과재료학회지 Vol.22 No.2
This study was performed to evaluate the effect of surface roughness on the flow of a 14K gold solder and the tensile strength of solder joints in titanium. To evaluate the flow of 14K gold solder on titanium, the spreading area of solder 10mg at 840℃ was measured on the titanium plate of 15 ×15 ×1mm. Two pieces of titanium rod 30mm in length and 3mm in diameter were butt-soldered using a electric resistance heating and tensile test was subjected to a crosshead speed of 0.5mm/min. Titanium surfaces were polished with #80∼#2000 emery paper and blasted with 50㎛ glass bead or alumina. The solder-matrix interface region was analyzed by EPMA. The results obtained were summarized as follows ; 1. Maximum spreading area was obtained when the surfaces were polished with #240 emery paper, the spreading area decreased with the decrease of surface roughness. 2. Maximum tensile strength value was 398.18 ±15.82 MPa when the soldering surfaces were polished with #2000 emery paper, and tensile strength increased with the decrease of surface roughness. 3. EPMA data for the solder matrix interface region revealed that the diffusion of Au and Cu occured to the titanium matrix, and the reaction zone in the solder showed the increase of Au, Cu, and Ti.
박일,추용호,이철로,이오연,Park Il,Chu Yong Ho,Lee Chul Ro,Lee Oh Yeon 한국재료학회 2004 한국재료학회지 Vol.14 No.12
Production of titanium powder directly from tantalum oxides ($TiO_2$) pellet through an electronically mediated reaction (EMR) by calciothermic reduction has been investigated. Feed material ($TiO_2\;pellet$) and reductant (Ca-Ni alloy) were charged into electronically isolated locations in a molten calcium chloride ($CaCl_2$) bath at $950^{\circ}C$. The current flow through an external circuit between the feed (cathode) and reductant (anode) locations was monitored during the reduction of $TiO_2$. The current approximately 3.2A was measured during the reaction in the external circuit connecting cathode and anode location. After the reduction experiment, pure titanium powder with low nickel content was obtained even though Ca-Ni alloy was used as a reductant. These results demonstrate that titanium powder can be produced without direct physical contact between the feed and reductant. In certain experimental conditions, pure titanium powder with approximately $99.5\;mass\%$ purity was successfully obtained.
광중합형 복합레진 제조시의 압축강도에 관한 실험적 연구
배태성,추용호,채민수 大韓齒科器材學會 1995 대한치과재료학회지 Vol.22 No.2
This study was performed to elaluate the effect of matrix resins and fillers on the compressive strength of light-activated composite resins. Four different types of composites were made by mixing the inorganic fillers of armorphous spherical silica and crushed quartz with resins of BisGMA/TEGDMA and UTeMA/TEGDMA. The specimens of 3mm in diameter and 6mm in length were prepared. Compressive test was subjected to a crosshead speed of 0.5mm/min and fracture surfaces were examined by SEM. The results obtained were summarized as follows; 1. Compressive strength of the UTeMA-based composite resin with spherical filler was superior to the other composite resins(p<0.01). 2. Compressive strength of the BisGMA-based composite resins with significantly decreased after immersion in water for 7 days(p<0.05). 3. UTeMA-based composite resins showed the aspect of decrease in compressive strength after cold storage at 5℃.
이민호,추용호 대한의용생체공학회 1993 의공학회지 Vol.14 No.4
The high biocompatibility of titanium is connected with the high corrosion resistance of the surface oxide, its high dielectric constant, and some other specific biochemical properties of the oxide. The corrosion resistance of titanium can be improved with the formation of passive film by anodic oxidation. In other to characterize the titantium oxlde film formed by anodic oxidation, titanium plates were anodized in 0.5M $H_3SO_4$ electrolyte at voltages between 5V and 100v. The oxide film was examined by an X-Ray Diffractometer(XRD) and a Scanning Electron Microscope(SEM). In addition, the corrosion resistance of oxide film was tested by dipping in physiological NaCl,5% HCI,5% $H_3PO_4$ and its biocompatability was evaluated by the fibroblast-like cell culture. The results obtained are as follows : 1. The thickness of surface oxide and micropore are increased with the increase of electrode potential and formed deeply along the grain boundary. 2. The solubilities of titanium in electrolyte solution shows that the anodized titanium has more corrosion resistance than the untreated pure titanium. 3. The biocomatibility of anodized titanium is superior to untreated pure titanium.
합금화용융아연도금강판의 미세파괴거동에 대한 In-situ 관찰
문현수,부현덕,추용호,안병국,김영근,안행근,Mun Hyun-Su,Bu Hyun-Duck,Chu Yong-Ho,Ahn Byung-Kuk,Kim Young-Geun,Ahn Haeng-Keun 한국재료학회 2004 한국재료학회지 Vol.14 No.9
In-situ observation in SBM on the microfracture behavior of coating layer was performed for GA steel sheets that have various Fe contents and thickness of coating layer. In case of cross sectional side of coating layer that was in a tensile stress state during bending, fine perpendicular crack pre-induced during galvannealing grew and propagated rapidly toward the coating surface with the increase of strain. And then it grew and propagated along the ${\Gamma}/Fe$ matrix interface, and combined with the nearest another perpendicular crack. Consequently, flaking occurred. The more Fe content and thickness of coating layer increased, the more average crack interval and flaking resistivity increased. Exfoliation was little observed at coating surface in a tensile stress state.
Sn-4.0wt%Ag-0.5wt%Cu 솔더 접합계면의 강도특성과 미세파괴거동에 대한 In-situ관찰
이경근,최은근,추용호,김진수,이병수,안행근,Lee, Kyung-Keun,Choi, Eun-Geun,Chu, Yong-Ho,Kim, Jin-Soo,Lee, Byung-Soo,Ahn, Haeng-Keun 한국재료학회 2008 한국재료학회지 Vol.18 No.1
The micro-structural changes, strength characteristics, and micro-fractural behaviors at the joint interface between a Sn-4.0wt%Ag-0.5wt%Cu solder ball and UBM treated by isothermal aging are reported. From the reflow process for the joint interface, a small amount of intermetallic compound was formed. With an increase in the isothermal aging time, the type and amount of the intermetallic compound changed. The interface without an isothermal treatment showed a ductile fracture. However, with an increase in the aging time, a brittle fracture occurred on the interface due mainly to the increase in the size of the intermetallic compounds and voids. As a result, a drastic degradation in the shear strength was observed. From a microshear test by a scanning electron microscope, the generation of micro-cracks was initiated from the voids at the joint interface. They propagated along the same interface, resulting in coalescence with neighboring cracks into larger cracks. With an increase in the aging time, the generation of the micro-structural cracks was enhanced and the degree of propagation also accelerated.